Coaxial cables with foam dielectric

Abstract

A dielectric system for coaxial electrical conductors is provided. The dielectric system separates an inner and an outer conductor and is composed of a first layer of cellular polyparabanic acid. This layer directly contacts and provides a continuous skin circumferentially surrounding the inner conductor along its length. A second layer, consisting of a crosslinkable polymeric lacquer which provides a continuous skin enclosing the first layer is also provided. The dielectric system is used in coax cables.

What I claim and desire to protect by Letters Patent is: 
     
       1. A coaxial cable comprising: a. an inner conductor;   b. a dielectric system surrounding said inner conductor, said dielectric system comprising: (i) a first layer of cellular polyparabanic acid providing a continuous skin directly contacting and surrounding said inner conductor along its length, and   (ii) a second layer consisting of a crosslinkable polymeric lacquer providing a continuous skin enclosing the first layer;     c. an outer conductor disposed circumferentially about the dielectric system;   d. an outer protective layer surrounding circumferentially the outer conductor.   
     
     
       2. The coaxial cable of claim 1 in which the first layer of cellular polyparabanic acid is in the form of a continuous tape wrapped about the inner conductor. 
     
     
       3. The coaxial cable of claim 2 in which the tape is wrapped about the inner conductor in an overlapping arrangement such that approximately 25% of the tape of one layer overlaps an adjacent layer.